Burner with Adjustable Injection of Air or of Gas

Abstract

A burner that includes a primary air or gas duct delimited by an exterior wall and a concentric interior wall of axis X and ducts for radial primary air or gas injection is described. The air or gas duct includes a ring that is rotationally mobile and has axial protrusions constituting distributors which collaborate with the radial primary air ducts arranged on the interior wall and form two passages of different angles in each duct. Rotating the ring making it possible to vary the angle of injection of the radial primary air. Thus, the regulation is situated just at the tip of the burner, in the region of the outlet of the primary air into the kiln, by modifying the outlet angle of the radial component for fixed section, thereby greatly simplifying the regulating of the burner.

Claims

1.-14. (canceled)

15. A burner comprising a primary air or gas duct having an axis delimited by an exterior wall and a concentric interior wall; radial ducts for gas or primary air injection, a rotatable ring arranged on an exterior peripheral part of the interior wall and having axial protrusions to define a plurality of distributors that cooperate with the radial ducts to form two passages of different angles in each radial duct.

16. The burner according to claim 15, wherein the ring is translationally mobile.

17. The burner according to claim 15, wherein the two passages are formed by complementary flared shapes of one of the plurality of distributors and of the radial duct or the primary duct, and wherein a sum of sections of the passages is constant in a plane perpendicular to the longitudinal axis, whatever angular position of the ring.

18. The burner according to claim 15, wherein the distributors and the radial ducts or primary ducts have walls with parallel edges.

19. The burner according to claim 15, wherein the distributors and the radial ducts or primary ducts have curvilinear edges.

20. The burner according to claim 15, wherein the radial ducts and the distributors are chamfered at an upstream end.

21. The burner according to claim 15, further comprising axial primary air ducts.

22. The burner according to claim 21, wherein the radial ducts are sandwiched between the primary duct and the axial primary air duct.

23. The burner according to claim 22, wherein the axial primary air duct and the radial ducts are fed from the same supply.

24. The burner according to claim 21, wherein an amount of radial ducts is a multiple of an amount of axial primary air ducts or an amount of a group of axial primary air ducts

25. The burner according to claim 24, wherein the radial ducts and axial primary air ducts are arranged on the same radii.

26. The burner according to claim 19, wherein the ring has at least one slot arranged in an inclined manner with respect to the axis, wherein an inclination and length of the at least one slot is proportional to rotation of the ring.

27. The burner according to claim 17, wherein the radial ducts have an outlet section that varies as a function of the movement of one wall with respect to the other, an interior radial face of the distributors and an external radial face of notches provided on the interior wall make an angle a with the axis, and an interior radial face of an exterior annulus makes an angle β with the axis.

28. The burner according to claim 16, wherein the distributors and the radial ducts have a complementary flared shape, forming two passages and of which the sum of the sections is variable in a plane perpendicular to the axis, whatever the angular position of the ring.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Further advantages may yet become apparent to those skilled in the art from reading the examples below, illustrated by the attached figures given by way of example:

[0051] FIG. 1 is a view in cross section of a gas or air circuit of the burner according to the invention,

[0052] FIG. 2 is a front view of the burner according to one particular arrangement,

[0053] FIGS. 3 to 5 show various positions of a curved-edges distributor in a radial primary air duct,

[0054] FIGS. 6a and 6b are development views of the distributor in the two extreme positions,

[0055] FIG. 7 is a view of the ring,

[0056] FIG. 8 is a view of the main duct,

[0057] FIGS. 9 to 12 show front views of various arrangements of the fuel and primary air circuits at the burner,

[0058] FIGS. 12 and 13 show a view in cross section of the burner in a particular arrangement in which the section of the gas or air circuit is adjustable. FIG. 12 is in the position of maximum section and FIG. 13 in the position of minimum section,

[0059] FIGS. 14 and 15 show a view in cross section of the burner in a particular arrangement in which the section of the gas or air circuit is adjustable by axial movement of the distributors. FIG. 14 is in the position of maximum section, and FIG. 15 is in the position of minimum section,

[0060] FIGS. 16a and 16b show various positions of the curved-edges distributors in a radial primary air duct,

[0061] FIGS. 17 and 18 show a view in cross section of the burner in a particular arrangement in which the section of the gas or air circuit is adjustable.

DETAILED DESCRIPTION

[0062] In the remainder of the description “downstream” will be the term used for parts positioned on the side of the arrival of the primary air and “upstream” will be the term used for those placed on the side of the outlet of the primary air.

[0063] The burner 1 comprises at least one gas or primary air duct 22 comprised between an exterior wall 52 and an interior wall 23 of axis X and constituting concentric tubes of cylindrical shape surrounding the centre of the burner 10 in which several other fuel or primary air ducts 100, 101 or a stabilizer 8 may be installed. The kiln-end of this duct is closed by an interior end annulus 2 and an exterior end annulus 5, which depending on the embodiment may be two distinct components in order to make machining easier, or one and the same component.

[0064] The gas or primary air duct comprises a ring 3, itself surrounded by a collar 4. The downstream end of the duct is encircled by the annulus 5. As may be seen in FIGS. 1, 2 and 8, the interior annulus 2 connected to the interior tube of the wall 23 has on its periphery notches 20 which have two faces 200 and 201 flaring apart from one another (or in the shape of a V), which are closed at their peripheral part by the annulus 5 thus constituting radial primary air ducts 21.

[0065] In an advantageous arrangement illustrated, the exterior annulus 5 comprises primary air ducts 50 with an axial component.

[0066] The ring 3 (cf. FIGS. 1, 2 and 7) has protrusions 30 of flared or V shape which are arranged in the notches 20 and constitute air distributors 30. Each protrusion 30 has two faces 300 and 301 which meet downstream and which are respectively parallel to the faces 200 and 201 of the notch 20. The V-shape therefore has its point facing downstream.

[0067] The ring 3 turns about the axis X on the main duct between two extreme positions, in which the distributor 30 is in abutment against the face 200 of the notch 20 or against the face 201 of the said notch 20. The ring 3 has at least one slot 31 arranged inclined with respect to the axis X.

[0068] In one particular arrangement illustrated, the collar 4 slides from upstream to downstream along the wall 23 along the axis X. The collar 4 has a pin, nut or key 42 which slides in the slot 31. The collar 4 is fixed to at least one control arm or rod 43 connected to a piston (not depicted) so as to cause the collar 4 to slide from upstream to downstream and vice-versa.

[0069] The operation of the burner 1 illustrated by FIGS. 3 to 5, 6a and 6b will now be described.

[0070] Each air distributor 30 allows the gas or primary air stream arriving in the gas or radial primary air duct 21 to be divided, and given a radial angular component by splitting it into two passages 210 and 211 with different angles. These passages 210 and 211 generate two jets which recombine into a single jet at the outlet and the mean angle of which is practically proportional to the outlet angle of each V, weighted by the flow rate of each jet. By rotating the ring 3 the distribution of section between the two passages 210 and 211 is varied, the overall section of the passages 210 and 211 being constant throughout the range of adjustment and therefore the flow rate in each of the branches of the V in order to obtain a variation in the outlet angle of the stream of air 6 without reducing the speed of ejection thereof and keeping the flow rate constant.

[0071] The gas or radial air component can thus be regulated by regulating the outlet angle of the jet, for the same pressure, for the same flow rate and for the same section upstream of the outlet orifice, thereby maximizing the impulse of the jet.

[0072] In the embodiment depicted in FIGS. 3 to 5, the passages 210 and 211 are curved, so as to reduce the drop in pressure in the passages through the progressive way in which speed is acquired according to the radial component and allow the jet greater aerodynamic stability. Specifically, the curved shape gives the jet on the inside of the bend a speed of expansion that is slightly lower than that on the outside of the bend. That makes the mixing of the two jets at different angles less turbulent and therefore makes for a more stable resultant flow and makes the mean speed of the jet more optimal.

[0073] In FIG. 3, the distributor 30 is positioned substantially in the middle, and the quantity of air passing along the two passages is substantially identical. In FIG. 4, the distributor 30 is pressed up against the wall 200 and the majority of the air passes along the more inclined passage 210, so the air stream 6 is therefore more steeply inclined. By contrast in FIG. 5, the distributor 30 is pressed up against the wall 201 and the majority of the air passes along the less inclined passage 211 so the air stream 6 is therefore very weakly inclined.

[0074] In FIGS. 3 to 5, chamfers 303, 203 are provided at the inlet of the air distributor 30 and at the inlet of the passages 210 and 211 in a tangential plane or in a vertical plane.

[0075] In the view that is FIG. 2, the burner comprises protective concrete 7 on the outside, the exterior annulus 5 with the axial ducts 50, the interior annulus 2 with the radial primary air ducts 21, and the centre of the burner 10 delimited on the outside by the wall 23 comprising a circuit 100 for powdered and/or gaseous fuel, and other fuel circuits 101 and a central stabilizer 8.

[0076] This type of burner can be used both if it has a single gas or primary air outlet with only the primary air ducts 21 or multiple outlets with the gas or primary air ducts 21 and 50.

[0077] In the case of a multiple primary air outlet, the ducts 50 and 21 may be fed with primary air from one and the same single primary air circuit 22 or by separate primary air circuits, which are generally concentric or near-concentric with respect to the axis X.

[0078] FIGS. 9 to 11 show various radial arrangements of the gas or primary air circuits according to the invention and of the annular fuel (powdered, gaseous fuel) circuit or circuits.

[0079] FIG. 9 shows an arrangement with, starting from the centre of the burner, at the centre a stabilizer 8, fuel circuit 101 in the stabilizer, a powdered-fuel circuit 100, a radial gas or primary air circuit with ducts 21, an axial circuit with ducts 50.

[0080] FIG. 10 shows an arrangement with, starting from the centre of the burner, in the centre a stabilizer 8, fuel circuit 101 in the stabilizer, a radial gas or primary air circuit with ducts 21, a powdered-fuel circuit 100, an axial circuit with ducts 50.

[0081] FIG. 11 shows an arrangement with, starting from the centre of the burner, at the centre a stabilizer 8, fuel circuit 101 in the stabilizer, a powdered-fuel circuit 100, a radial gas or primary air circuit with ducts 21 without an axial circuit.

[0082] Other arrangements which have not been depicted, such as, for example, with the powdered-fuel circuit 100 on the outside, are also possible.

[0083] In certain applications and advantageously illustrated in FIGS. 12 and 13 the gas or radial primary air circuit 22, the minimum section of the radial component in the plane 216 can be adjusted at the tip of the burner in order to maintain a maximum pressure and therefore a maximum speed of injection of the gas or of the primary air at the tip of the burner. This modification to section is obtained by the moving along the axis X of one of the walls 23 or 52 with respect to the other, from the angular inclination a of the interior radial face 315 of the distributors 30 and the exterior radial face 215 of the gas or radial primary air notches 20 with respect to the axis X, and a divergent angle β on the interior radial face 51 of the exterior annulus 5. For preference, the interior wall 23 is mobile and the exterior wall 52 is fixed.

[0084] In FIGS. 16a or 16b, the ring 3 also undergoes translational movement along the axis X on the main duct between two extreme positions in which the face 310 of the distributor 30 is in abutment on the face 220 in order to obtain a minimum passage section. The distributor 30 can be moved back for an increased passage section. The translational movement of the ring 3 or even the rotation thereof can be achieved using two independent relative movements. Section adjustment may also very well be achieved by a translational and/or rotational movement of the ring.

[0085] In the applications illustrated in FIGS. 14 and 15, in the gas or radial primary air circuit 22, the section of the radial component may be adjusted at the tip of the burner 1 in order to maintain a maximum pressure and therefore a maximum speed of injection of the gas or of the primary air at the tip of the burner. This modification to section is obtained by the translational movement along the axis X of the ring 30 connected to the control rod 43. In the retracted position, FIGS. 14, 16a and 17, the section of the passages 210, 211 are at a maximum, whereas when pushed, FIGS. 15, 16b and 18, the section of the passages 210, 211 is at a minimum.

[0086] It may be seen from FIGS. 17 and 18 that the translational movements of the ring 30 take place along the axis X and are controlled by the tube or control rod 43, whereas the rotational movement of the ring 30 is obtained by the translational movement of the tube or of the control rod 43.

[0087] The optimal arrangement for drawing secondary air into the flame is to install this primary air circuit on the outside of the fuel circuits and notably the powder circuit. This arrangement limits the expulsion of solid fuels on the outside of the flame and reduces the formation of nitrogen oxides.

[0088] In the context of a burner having multiple air outlets, having this device situated just on the outside of the fuel circuit as illustrated in FIG. 2, notably the powdered fuel (carbon, pet coke, etc.) circuit and generally between the powdered-fuel circuit and the axial circuit means that it can be rotated in order to activate its combustion but that it also enjoys the benefit of the outlet orifices of the primary air circuit with a tangential component being arranged close to the secondary air so that the impulse of this circuit can be put to good use for absorbing secondary air into the flame.

[0089] In the configuration depicted in FIG. 10, the number of ducts 21 is a multiple of the number of axial ducts 50 or of groups of axial ducts 50, in order to improve the absorption of secondary air.

[0090] This is optimal when the number of ducts 21 is identical to the number of axial ducts 50 or groups of axial ducts 50 and when the ducts 21 are on the same radii as the ducts 50 or groups of ducts 50.